Missing link ties older to newer dinosaurs

WASHINGTON - The surprising discovery of a fossil of a
sharp-toothed beast that lurked in what is now the western U.S.
more than 200 million years ago is filling a gap in dinosaur
evolution.

The short snout and slanting front teeth of the find -
Daemonosaurus chauliodus - had never before been seen in a Triassic
era dinosaur, said Hans-Dieter Sues of the Smithsonian's National
Museum of Natural History. Sues and colleagues report the discovery
in Wednesday's edition of the British journal Proceedings of the
Royal Society B.

Sues, curator of vertebrate paleontology at the museum, said the
discovery helps fill the evolutionary gap between the dinosaurs
that lived in what is now Argentina and Brazil about 230 million
years ago and the later theropods like the famous Tyrannosaurus
rex.

Features of the skull and neck of Daemonosaurus indicate it was
intermediate between the earliest known predatory dinosaurs from
South America and more advanced theropods," said Sues. "One such
feature is the presence of cavities on some of the neck vertebrae
related to the structure of the respiratory system."

Daemonosaurus was discovered at Ghost Ranch, N.M., a well-known
fossil site famous for the thousands of fossilized skeletons found
there, notably the small dinosaur Coelophysis. Ghost Ranch was more
recently the home of artist Georgia O'Keeffe, who was known to
visit the archaeological digs under way there, Sues noted.

Having found only the head and neck of sharp-toothed
Daemonosaurus, the researchers aren't sure of its exact size but
they speculate it would have been near that of a tall dog. Its name
is from the Greek words "daimon" meaning evil spirit and
"sauros" meaning lizard or reptile. Chauliodus is derived from
the Greek word for "buck-toothed" and refers to the species' big
slanted front teeth.

"It looks to be a mean character," commented paleontologist
Paul Sereno of the University of Chicago, who was not part of the
research team. "I can't wait to see if they get any more of the
skeleton."

This fits in quite nicely between the dinosaur groups, Sereno
said, even though its face is unlike anything that would have been
expected in these early dinosaurs, which tended to have more
elongated snouts.

This find shows there is still much to be learned about the
early evolution of dinosaurs. "The continued exploration of even
well-studied regions like the American Southwest will still yield
remarkable new fossil finds," Sues said.